Production of ammonium sulfate.



' UNITED THOMAS HILL nas'rnnrinnn, or WELLINGTON, NEW ZEALAND.

PRODUCTION OF AMMONIUM SULFATE No Drawing.

To all whom it may concern 1 Be it known that I, THOMAS Him. Easrnn-FIELD, a citizen of the Dominion of New Zealand, and resident ofTalavera Terrace, ellington, in the Provincial District of lVellington,Dominion of New Zcaland, have invented certain new and usefulImprovenlents Relating to the Production of Ammonium Sulfate, of whichthe following is a specification. 7

It has long been known that the ammoniacal liquor obtained by washingcrude distillation gases such as blast furnace gases, coke oven gases,or coal gas can he made to yield sulfate of ammonia by interaction withcalcium sulfate. The chief drawback of existing processes consists inthe very large consumption of fuel-required in the evaporation of thedilute solution of ammonium sulfate which results. Typical gas liquorcontains about 1-1-% and seldom contains morethan 3% of ammonia andafter conversion will accordingly not contain above 12% of ammoniumsulfate. In a process patented in Great Britain by Feld in 1891 underthe Number 27567, the gas is washed with water containing calciumsulfate in suspension, the washing being continued until a sufficientlyconcentrated solution is obtained.

According to my invention, in order to obtain a concentrated solution ofammonium sulfate I proceed as follows :The ordinary gas liquor (which'consists mainly of a dilute solution of ammonium carbonate) afterseparation as completely as convenient from particles of tar is agitatedwith calcium sulfate or is passed through one or more percolators packedwith calcium sulfate and,

the resulting solution of ammonium sulfate is returned to the gaswashing apparatus to be recharged with ammonia and carbon dioxid andsubsequently again treated with calcium sulfate, the process beingcontinued until a concentrated solution of ammonium sulfate is obtained.

Another method is to concentrate the gas liquor by distillation, a wellknown process, retaining in the distillate as much carbonic acid aspossible, and the resulting concentrated solution is then to be dilutedwith Specification of Letters Patent.

Patented Sept. 9, 191.3.

Application filed January 2, 1913. Serial No. 739,836.

water to such an extent that during treatment with calcium sulfateno'ammonium salts will crystallize out and then to allow the concentrateto react with calcium sulfate either by agitation or percolation. Theliquor arising from either of these processes is first submitted topartial distillation so as to drive off and recover any volatileammonium salts which are returned' to be recarbonated and converted tosulfate. The liquor which is now free from sulfated hydrogen isevaporated and the ammonium sulfate recovered.

Either of the methods of carrying out the concentration may be modifiedby carbonating or desulfurizing or decyanidizing or carbonating anddesulfurizing and decyanidizing the liquor before, during or after theprocess of interaction with calcium sulfate.

The interaction with the calcium sulfate may with advantage be carriedout at a temperature higher than that of the atmosphere in order toincrease the rapidity of action.

What I do claim and desire to secure by Letters Patent of the UnitedStates is 1. The herein described process of obtaining ammonia fromgases which comprise reacting upon ammoniacal liquor containing ammoniumcarbonate with calcium sulfate; separating the precipitated calciumcarbonate' from the solution of ammonium sulfate formed, and thereafterwashin gases containing ammonia and carbon dioxld with said solution ofammonium sulfate.

2. The herein described process of making ammonium sulfate whichcomprises reacting upon ammoniacal liquor containing ammonium carbonatewith calcium sulfate; separating the precipitated calcium carbonate fromthe solution of ammonium sulfate formed, and thereafter washin gasescontaining ammonia and carbon dioxld with said solution of ammoniumsulfate, and thereafter alternately treating said liquor with calciumsulfate and with gases containing ammonia and carbon dioxid, andseparating ammonium sulfate from the liquor after the step of treatingthe same with calcium sulfate.

3 In the process of obtaining solutions of ammonium sulfate from gasescontaining ammonia and carbon dioxid, the improvement which comprisestreating the same name to this specification in thepresence of twowitnesses.

THOMAS HILL EASTERFIELD.

Witnesses:

T. SHAImm WESTON, CECIL BALFOUR MELVILLE.

